In the use of plastic containers, it becomes necessary to apply labels. It has been found that applying the labels during the molding process reduces costs of manufacture and produces an attractive container. More specifically, when a hollow parison or preform is expanded against the surface of the mold having a label on a side wall of the mold cavity so that when the plastic is expanded, it causes an adhesive on the label to be heated and thereby adhere the label to the container. One common type of label that is used is a paper label. However, the use of such a label has inherent problems in that when the plastic container cools, the plastic and paper have different rates of shrinkage and, as a result, the paper wrinkles and stresses occur in the adhesive. Another problem with the use of paper labels is that any rejected containers cannot be reprocessed until the paper label is removed. It is therefore been common to discard the entire container or, at most, cut off the neck of the container and discard the remainder.
Expired U.S. Pat. Nos. 3,108,850 and 3,207,822 discuss the use of plastic labels without adhesive. Pat. No. 3,108,850 contemplates the use of an insulator comprising a paper layer or plastic layer between the mold and the plastic parison. The insulating part is connected to the label by either a temporary readily strippable connection for quick removal or a relatively permanent connection so that the insulation remains with the label on the completed container to form the decorated outer surface. Pat. No. 3,207,822 contemplates a plastic label made of a material similar to that used in making the bottle that becomes bonded to the container by the heat and pressure of blowing the container. The patent also contemplates coarsely roughening the surface of the mold to facilitate bonding of the label to the container. As far as I am aware, such efforts were not commercially successful and, at the present time, adhesive is used in all labels wherein the labels are applied by the inmolding process.
Accordingly, there is need for providing a blown plastic container which has a label applied by the in-mold labeling process that avoids the use of adhesive; which is low in cost; which results in a container that is readily recyclable; and which produces an attractive appearance offering various aesthetic effects.
In accordance with the invention, the plastic container embodying the invention comprises a plastic container having a multilayer label applied by in-mold labeling during the blow molding of the plastic container. The label comprises a non-cellular inner layer, an intermediate cellular layer compatible with the inner layer and heat bonded to the inner layer, and an outer non-cellular plastic layer compatible with the intermediate cellular layer and heat bonded thereto. The label is positioned in a mold cavity with the outer layer in contact with the mold. When a hot plastic parison at molding temperature is expanded by fluid pressure against the walls of the mold to form a container, the non-cellular inner layer becomes bonded to the outer surface of the container by heat from the container.